Hi @arskrigitsioniets
Generators are working from cache, so they look for new data once the cache time expires: https://smartslider3.helpscoutdocs.com/article/88-generator-functionality#cacheexpiration
Are you using the latest version of Smart Slider 3? Because the WordPress post generator, should automatically clear its cache since a couple of versions when a new post is added.
Do you have a 3rd party page caching on your site? The problem can be that the slider’s cache was cleared after the new post added, but this 3rd party plugin didn’t yet clear its own cache. The way caching plugins work is that they save down your site’s static code, and keep showing that until their own cache is cleared. So this cache plugin can show the page where your slider is in the state, where the 6th post didn’t exist yet.
If you’re using a caching plugin, can you tell me which one?
If you write the ID of the page/post where the slider is published to the Slider settings > Developer tab > Post IDs (one per line) field: https://smartslider3.helpscoutdocs.com/article/1294-slider-settings-developer
Do you see the new post appear sooner than before?